1. Field of the Invention
The present invention relates generally to the field of gas turbine engine maintenance. More specifically, the present invention relates to the field of predicting and trending the failure of the starter control valves of gas turbine engines.
2. Description of Related Art
Gas turbine engine starter control valves are used to regulate the initial mechanical energy needed for accelerating a gas turbine engine to an initial speed before fuel ignition occurs in the gas turbine engine which creates and imparts additional thermal energy for bringing the engine to the desired speed for take-off as the starter control valve is controlled by the pilot of the aircraft using electronic control signals, such as a starter button. A failure in the starter control valve subsystem can result in the pilot's inability to regulate the pre-start process of the gas turbine engine thereby preventing the engine from reaching an initial speed that the engine must obtain before fuel ignition occurs in the gas turbine engine. The inability of an engine to reach the speed required for fuel ignition prevents the engine from starting and can therefore result in a flight or mission cancellation, especially if the engine is required to be operational for takeoff.
Although a starter control valve failure often manifests itself as a failed gas turbine engine start attempt followed shortly by a successful gas turbine engine start, in some instances, a starter control valve failure prevents the gas turbine engine from being started and can accordingly result in the cancellation of a flight. A starter control valve failure can even result in a mission cancellation. Presently, operational crews log failed start attempts, and such logs are analyzed to provide a repair recommendation or action. However, no system, method, or computer program product exists to proactively detect a starter control valve failure prior to its occurrence. Thus, under present systems, the replacement of a starter control valve occurs only after a complete starter control valve failure resulting in the inability of a pilot to start an engine, or after multiple failed start attempts have been observed. The inability to proactively detect starter control valve failures can result in the allocation of ill-prepared aircraft to critical missions thereby producing increased costs due to mission aborts and aircraft reallocation. Additionally, the unscheduled occurrence of starter control valve failures can also result in reactive, rather than proactive, maintenance practices and related practices and processes on supply-chain and aircraft inventory management that can ultimately lead to increased costs and increased aircraft unavailability and downtime.
Systems and methods to detect a starter control valve failure are known, however, such systems and methods are incapable of accurately predicting the point of failure of a starter control valve prior to the event of failure. Other systems and methods are known that proactively predict the possibility of an aircraft component failure, however, these systems and methods fail to identify how to predict the failure point of a starter control valve prior to an event of failure. Still other systems and methods, at least to some extent, trend and predict the failure of gas turbine engine components by analyzing currently gathered aircraft performance data against historical data and past trends within the historical data. Such systems and methods, however, require detailed knowledge of an aircraft component in its “as new” state in order to trend the failure of that component.
Although such a system and method can function at least to some extent for newer aircraft components for which a full “as new” operational data history is known, older legacy components, including starter control valves, can lack such a sufficient historic data record thereby resulting in inaccurate predictions of failure when this method is applied to try to proactively determine starter control component failure prior to an actual event of failure. Therefore, the inventors have recognized that the ability to predicitvely detect starter control valve failures can be directly related to the minimization of operational costs due to aircraft mission aborts, aircraft cancellations, and aircraft mission aborts.
The inventors, therefore, have recognized the need for machines, systems, computer program products, and related computer implemented methods to proactively predict and trend starter control valve failures in gas turbine engines using a starter control valve health prognostic. Although rudimentary systems and methods which can, to some extent, predict and trend engine component failure are known, none employ a starter control valve health prognostic responsive to historic performance data, (as opposed to hypothetical “as new” performance data), to precisely identify the point of failure for a starter control valve prior to the component's actual failure. Additionally, the inventors have recognized the need for machines, systems, computer program products, and related computer implemented methods to identify a projected point of failure for a starter control valve by constructing a continuous starter control valve deterioration trend function responsive to current operational data so that a precise failure point can be identified far in advance of an actual event of failure. Although prior systems and methods employ trend functions to aid in the prediction of a point of failure for an engine component, such systems and methods analyze past trends in general historic aircraft engine startup data rather than trending presently collected engine startup data to construct a continuous starter control valve deterioration trend that can be compared to a starter control valve health prognostic to determine future points of failure for starter control valves.